Cellulose gelation in NaOH solutions is due to cellulose crystallization

Cellulose gelation in 2 M NaOH aqueous solution was followed by time resolved turbidity and rheology measurements. The kinetics of gelation is observed to change from several hours down to few seconds when the temperature is increased from 25 to 30 °C. The increase of turbidity upon gelation demonstrates the formation of larger cellulose aggregates, while wide angle X-ray scattering data confirms the gradual formation of crystalline domains. This suggests that the gelation can be understood as cellulose precipitation/crystallization where an effectively cross linked network and gelation results from that cellulose chains may participate in more than one crystallite.